1.1 TECHNICAL FIELD
This invention relates to grasping and moving light weight objects. In many industries, processes, and hobbies there is a need to grasp and manipulate small objects that are difficult to grasp with a human hand. Grasping an object may be difficult due to the objects size, its shape, its orientation, its location relative to other objects or in space restricted areas. Some objects are fragile and may be damaged if gripped by the human hand or other mechanical grasping means. Other handling situations are sensitive to contamination by skin oils if touched or grasped by the human hand. Still other handling circumstances involve objects that are at an elevated temperature too hot to handle from a personal safety standpoint. In these predicaments it would be advantageous to have a hand held tool that would not impart mechanical damage or contamination to the object being manipulated and would protect the person using the tool from unsafe conditions.
One area in which such a hand held tool would prove to be useful is the semiconductor production industry where wafers used in the production of integrated circuits are handled. The device may be used to pick-up and move wafers from one processing location to another. Contamination of a wafer during the clean room processing operations could result in defective chip locations in the finished semiconductor wafer. After the wafers are diced and sealed into integrated circuit packages, the hand held tool could be used to grasp the integrated circuits to place them in test fixtures or shipping containers. Some of the tests are performed in elevated temperature processing ovens therefore, the components may be hot during handling. Similarly, the same device may be used in the placement of electronic components onto circuit boards during the assembly operations in the electronics industry. Additionally, small components used in various hobbies or other industries involving installation of small parts may be easily grasped and positioned using such a hand-held vacuum-handling tool.
1.2 BACKGROUND ART
Devices which attempt to accomplish the task of grasping and manipulating small objects are known in prior art. Such devices have limitations that have been solved by the device described in this specification. Limitations include devices that are tethered with vacuum hoses or electrical cords. Such cords and tubes encumber the devices and restrict freedom of movement from one location to another to accomplish handling operations. One such tool is described in U.S. Pat. No. 4,822,278 to Oliva. This instrument is connected to an external vacuum source by way of a vacuum hose. Such a tool encumbered by a vacuum hose restricts freedom of movement from one location to another. This tool can only be used in a confined area during the handling operations. Additionally, the probe is mounted in such a fashion that the entire tool must be maneuvered to accomplish various handling orientations of the curved probe. The tool described in this specification solves this problem with a nozzle that is rotatably attached with an internal friction washer that provides resistance to unwanted rotation as well as the ability to rotate the probe to any orientation.
Other portable suction handling devices are known in the prior art. Thus, U.S. Pat. Nos. 4,123,098 to Shoup, 3,879,076 to Barnett, 4,017,272 to Drdlik, 5,106,139 to Palmer, 4,079,976 to Raninin and 4,332,408 to Cointment all describe portable hand held vacuum handling devices. These devices, although hand held and very portable, lack a means to replenish the suction that is lost to air leaks between the gripping member and the object that is being handled. Air leaks are caused by irregularities in the object being handled, porosity of the surface of the object being handled, dust or other particles at the interface between the gripping member and the object being handled, and irregularities on the surface of the gripping member due to variations in the gripping member manufacturing process. As a result, the objects being handled with these devices can drop from the handling tool after a short period of time. The tool in this specification solves this problem by inclusion of an electrically-controlled vacuum pump that continuously compensates for suction loss to air leaks. Another dilemma associated with these tools surrounds their dependence upon a resilient bladder to create the suction. Suction created by this means falls in the range of 2 to 5 inches of mercury. This low level of vacuum does not have sufficient force to lift and hold objects in excess of 150 grams. The tool described in this specification solves this problem by providing vacuum in the range of 10 to 14 inches of mercury which is sufficient to reliably handle up to 250 grams of load.
Of those tools known in prior art for moving small light weight objects, each of them have obstacles associated with their design that precludes their use for many applications. Devices encumbered with hoses or cords restrict movement. In others, the lack of a means to provide sufficient vacuum or to replenish loss of vacuum due to air leaks severely restricts the size of the object that can be handled and the time period for which the objects can be handled. A hand-held device is needed that provides freedom of movement over a large area, maintains vacuum for an extended period of time, and furnishes sufficient vacuum to lift a wide variety of object sizes.